Toward Functional π-Conjugated Organophosphorus Materials: Design of Phosphole-Based Oligomers for Electroluminescent Devices

The photophysical, electrochemical, and optoelectronic properties of conjugated systems
incorporating dibenzophosphole or phosphole moieties are described. Dibenzophosphole derivatives are
not suitable materials for OLEDs due to their weak photoluminescence (PL) in the solid state and the
instability of the devices. Variation of the substitution pattern of phospholes and chemical modification of
their P atoms afford thermally stable derivatives, which are photo- and electroluminescent. Comparison of
the optical properties of solution and thin film of thioxophospholes shows that these compounds do not
form aggregates in the solid state. This property, which is also supported by an X-ray diffraction study of
three novel derivatives, results in an enhancement of the fluorescence quantum yields in the solid state.
In contrast, (phosphole)gold(I) complexes exhibit a broad emission in thin film, which is due to the formation
of aggregates. Single- and multilayer OLEDs using these P derivatives as the emissive layer have been
fabricated. The emission color of these devices and their performances vary with the nature of the P material.
Interestingly, di(2-thienyl)thiooxophosphole is an efficient host for the red dopant DCJTB, and devices using
the gold complexes have broad emission spectra.

本描述针对包含二苯磷杂环或磷杂环基团的共轭体系的物理光、电化学及光电子性质进行了阐述。鉴于二苯磷杂环衍生物因在固态下光致发光（PL）较弱以及器件不稳定，故不适宜用作有机发光二极管（OLEDs）的材料。通过对磷杂环取代模式的调整及其P原子的化学修饰，可得到热稳定性衍生物，这些衍生物具备光致和电致发光特性。对硫代磷杂环的溶液和薄膜的光学性质进行比较，发现这些化合物在固态下不形成聚集体。此特性亦得到三种新型衍生物的X射线衍射研究的佐证，从而在固态下提高了荧光量子产率。相比之下，（磷杂环）金（I）配合物在薄膜中表现出广泛的发射，这是由于聚集体形成所致。以这些P衍生物作为发射层的单层和多层OLEDs已被制备。这些器件的发射颜色及其性能随P材料性质的不同而变化。有趣的是，二（2-噻基）硫代氧磷杂环是一种高效的红色掺杂剂DCJTB的主客体材料，而采用金配合物的器件则具有广泛的发射光谱。